Circular stitching attachment for sewing machines



March 26, 1968 J. G. RAKACS 3,374,753

CIRCULAR STITCHING ATTACHMENT FOR SEWING MACHINES Filed Sept. 9, 1966 6| 3 25 60 2 2| 52 III 7 65 20 INVENTOR. George J. Rakacs Witness BY 1 Ina WETTORNEY United States Patent of New Jersey Filed Sept. 9, 1966, Ser. No. 578,198 4 Claims. (Cl. 1122) This invention relates to work guiding attachments for sewing machines and more particularly to sewing machine attachments adapted to provide a revolving center for work fabrics selectively positionable relatively to the stitching point of the sewing machine whereby stitching may be accomplished in accurate circles of selected diameter.

It is an object of this invention to provide a circular stitching attachment with a novel means for clamping the revolving work supporting center in selected position relatively to the stitching point with the attachment parts being secured rigidly and clamped in selected position yet releasable simply upon the touch of an operators finger for ready selection of an alternative position of parts.

With the above and additional objects and advantages in view as will hereinafter appear, this invention will be described hereinbelow as illustrated in the accompanying drawing in which:

FIG. 1 is a perspective view of a circular stitching attachment embodying the features of this invention illustrated as applied to a sewing machine bed,

FIG. 2 is a cross sectional view taken substantially along line 22 of FIG. 1 illustrating the clamp device for the work supporting arm of the attachment in effective position,

FIG. 3 is a cross sectional view also taken substantially along line 22 of FIG. 1 but illustrating the clamp device for the work supporting arm of the attachment released for selection of the position of the arm,

FIG. 4 is an enlarged perspective view of a fragment of the attachment base together with the attachment fastening screw illustrating the manner in which the screw is held captive in the attachment base, and

FIG. 5 is a cross sectional view, taken substantially along line 5-5 of FIG. 1, illustrating the details of construction of the rotating Work supporting center of the attachment.

As illustrated in FIG. 1, the attachment of this invention is adapted to be secured upon the work supporting surface 11 of a sewing machine bed 12. The sewing machine is of the type having an endwise reciprocable needle 13 which cooperates in the formation of stitches with a loop taker (not shown) beneath the work supporting surface 11 of the bed. The loop taker is carried within a cavity in the sewing machine bed which cavity is closed at the top by a throat plate 14 and also by a slide cover plate 15. Biased downwardly upon the throat plate adjacent to the needle is a conventional presser foot 16 which opposes a conventional work feed dog 17 working upwardly through slots in the throat plate to transport work fabrics transversely across the work supporting surface 11.

The circular stitching attachment of this invention comprises a rectangular stamped sheet metal base 20 formed with a planar rim or border 21 adapted to abut the sewing machine work supporting surface 11. Inwardly of the border 21 the base 20 is formed with an upwardly offset rectangular center section 22 which will thus be disposed spaced from but parallel to the sewing machine work supporting surface. At opposite sides of the rectangular center section 22 are formed with pairs of opposed struck-up ears 23 and 24 which together with the center section 22 define a channel snuggly accommodating "ice a rectangular shank 25 of a work pivot pin carrier arm 26.

The carrier arm 26 near the free extremity thereof is formed with an offset 27 and at the free extremity as illustrated in FIGS. 1 and 5 is formed with an upwardly offset circular boss 28. A shouldered rivet 29 is journaled in a central aperture 30 in the circular boss 28 with the head 31 of the rivet beneath the boss 28 and within the recess formed by the upward offset of the boss. A washer 32 is spun or crimped onto the rivet 29 above the circular boss 28 thus to constrain the rivet rotatably in the aperture 30. A tapered upstanding pin 33 is set substantially centrally into the rivet 29.

When work fabrics are placed upon the tapered pin the fabrics will be free to turn about the axis of the rivet 29. To constrain fabrics on the tapered pin a cylindrical cap 40 is provided. In a bore 41 in the cap is placed a plug 42 of resilient material such as rubber, cork, or the like, which plug is constrained in the bore 41 by a keeper disk 43 which is forced into a counterbore 44 in the cap. An aperture 45 in the keeper disk 43 accommodates passage of the tapered pin 32 into the plug 42.

Referring to FIGS. 1 and 4, the attachment base 20 is adapted to be secured upon the work supporting surface 11 of the machine bed by a single fastening screw formed with a knurled head 51, with a threaded shank 52, and with an annular neck 53 of reduced diameter between the threaded shank and the head. Struck down from the raised center section 22 of the attachment base is a depressed area 54 which extends substantially to the same level as the rim or border 21 of the attachment base. An elongate slot 55 is formed in the depressed area 54 to accommodate with slight clearance the annular neck 53. At one extremity, the slot 55 is widened as at 56 sufiiciently to pass the threaded shank 55 of the screw 50 and the attachment base is provided with a deformable tang 57 extending into the widened slot portion 56. With the tang 57 bent to one side, the threaded portion 53 of the screw may be inserted through the widened slot portion 56 after which the tang 57 is bent back into the plane of the rim or border portion 21 of the attachment base thus constraining the neck 53 of the screw 50 in the slot 55.

The screw 50 is adapted to be threadedly engaged in a conventional tapped attachment fastening hole (not shown) in the bed of the sewing machine. The elongated slot 55 provides for accommodation of differences in the location of such attachment fastening holes in different varieties of machines. The rectangular shape of the base 20 provides for location of the rim portion 21 along side 'the slide plate 15 of the sewing machine which is conventionally slightly proud of the work supporting surface 11 of the sewing machine, so that when the fastening screw 50 is tightened, the attachment base 20 will be locked against turning movement relatively to the bed and a particularly rigid fastening for the attachment base is provided.

The locking device whereby the distance between the tapered pin 33 and the sewing machine needle 13 may be selectively determined to vary the diameter of resulting circular patterns of stitches is best illustrated in FIGS. 1, 2, and 3.

The raised center section 22 of the attachment base 20 is formed between the struck-up ears 23 and 24 with an opening 60 which is preferably rectangular in shape and extends beyond both sides of the shank 25 of the carrier arm 26. Between the opening 60 and the depressed area 54 the center section 22 of the attachment base is formed with a small opening 61 preferably as wide as and in alignment with the opening 60. The openings 60 and 61 accommodate and support an operator influenced locking element 62 by which the shank portion 25 of the work supporting arm may be locked in selected position relatively to the attachment base 20. Preferably the v locking element as illustrated in the drawings, takes the form of a cantilever spring of which the free extremity 63 provides a finger grip portion which is offset upwardly by an inclined portion 64 from one end of a straight central section 65 which extends freely through the opening 60 beneath the shank portion 25 of the carrier arm. At the other end of the straight central section 65, the locking element is formed with an upwardly arched portion 66 which terminates in a short straight section 67 substantially co-planar with the straight central section 65.

The arched portionv 66 of the locking element 62 is formed with sufficiently small radius relatively to the dimension of the bridging section 68 of the attachment base between the openings 60 and 61 that when the extremity 67 of the spring is projected into the opening 61 before the shank 25 is inserted under the ears 23 and 24, the locking element will be anchored to the base 20 and by depression of the finger grip portion 63 the spring must be stressed into the position illustrated in FIGS.'2 and 3. When the shank 25 is to be inserted or the position of the pivot pin 33 is to be changed the finger grip portion 63, must therefore, be depressed as illustrated in FIG. 3 to withdraw the locking element out of engagement with the shank and permit the shank to be slid freely relatively to the ears 23 and 24. When the finger grip portion is released as illustrated in FIG. 2, the stress in the canti lever spring will force the inclined portion 64 against one corner of the shank 25 and thus force the shank sidewards against the ears 23 and 24 to lock the carrier arm securely in place. The force of the spring acting midway between the ears 23 and 24 deters rocking or tilting of the work supporting arm.

As illustrated in FIG. 1, a scale 70 may be marked on the shank 25 cooperable with indicia 71 on one of the ears 23 to show the distance of the tapered pin 33 from the sewing machine needle .13.

.As applied to a sewing machine, the offset 27 in the work supporting arm of the attachment places the tapered pin 33 laterally opposite the needle 13 considered in the conventional direction which the work fabric will be fed by the sewing machine feed. When work fabric is placed on the pin 33 and under the presser foot, therefore, the operation of the sewing machine will result in formation of a circular path of stitch formation.

base comprises spaced pairs of carrier arm embracing Having thus set forth the nature of this invention, what is claimed herein is:

1. A circular stitching attachment for a sewing machine having a work supporting bed, a thread engaging needle reciprocable in an endwise path relatively to said work supporting bed, and a work feeding mechanism effective adjacent to said needle path for transporting work fabric in a direction transversely across said work supporting bed, said attachment comprising a base, means for securing said base rigidly to said sewing machine work supporting bed, a work fabric engaging pivot pin, a carrier arm supporting said pivot pin, guide means on said base plate slidably constraining said carrier arm for movement lengthwise of said work supporting bed, a locking element engageable with said carrier arm adjacent to said guide means, spring means anchored on said base plate and biasing said locking element against said carrier arm, and an operator influenced finger grip associated with said locking element for at will shifting said locking element in opposition to said spring means out of V engagement with said carrier arm.

2. A circular stitching attachment as set forth in claim 1 in which said guide means on said attachment ears, and in which said locking element engages said carrier arm between said spaced pairsof ears. I 3. A circular stitching attachment as set forth in claim 1 in which said locking element, said spring means, and V said finger grip are formed by a single cantilever spring.

4. A circular stitching attachment as-set forth in claim 3 in which said attachment base is formed with an opening beneath said carrier arm, and in which said cantilever spring extends through said opening and is anchored on said attachment base at one side of said opening and formed with said finger grip portion at the opposite side. thereof.

References Cited UNITED STATES PATENTS 740,644 10/ 1903 Greist 1 12257 754,320 3/ 1904 Kiesewetter et a1 112-2 X 1,682,362 8/1928 Von Halle 112-2 X 2,148,987 2/1939 Hinman et al. 112257 2,717,566 9/1955 Szczepanski et a1 1122 X HERBERT F. ROSS, Primary Examiner. 

1. A CIRCULAR STITCHING ATTACHMENT FOR A SEWING MACHINE HAVING A WORK SUPPORTING BED, A THREAD ENGAGING NEEDLE RECIPROCABLE IN AN ENDWISE PATH RELATIVELY TO SAID WORK SUPPORTING BED, AND A WORK FEEDING MECHANISM EFFECTIVE ADJACENT TO SAID NEEDLE PATH FOR TRANSPORTING WORK FABRIC IN A DIRECTION TRANSVERSELY ACROSS SAID WORK SUPPORTING BED, SAID ATTACHMENT COMPRISING A BASE, MEANS FOR SECURING SAID BASE RIGIDLY TO SAID SEWING MACHINE WORK SUPPORTING BED, A WORK FABRIC ENGAGING PIVOT PIN, A CARRIER ARM SUPPORTING SAID PIVOT PIN, GUIDE MEANS ON SAID BASE PLATE SLIDABLY CONSTRAINING SAID CARRIER ARM FOR MOVEMENT LENGTHWISE OF SAID WORK SUPPORTING BED, A LOCKING ELEMENT ENGAGEABLE WITH SAID CARRIER ARM ADJAC- 